The present invention pertains to the art of weight verification. It finds particular application in weight checking packages, such as bundles of newspapers, to determine whether each bundle contains a preselected number of articles or newspapers. It is to be appreciated, however, that the invention finds utility in other applications in which weight is used to check the number of articles in a package, in which the article count of printed material bundles or packages is verified, and other applications in which the average weight of the articles may fluctuate.
Heretofore, it was proposed to weigh bundles of newspapers to determine the number of papers in each bundle. To set the tare, the typical weight of an individual newspaper was determined and multiplied by the number of newspapers per bundle, e.g., 25. The measured weight of each bundle was compared with the set tare. If the measured bundle weight was within a preselected tolerance, normally plus or minus half the typical individual newspaper weight, of the set tare, the bundle was considered acceptable. If the bundle was above or below the preselected tare by greater than this preselected tolerance, the bundle was considered to have too many or too few newspapers, respectively,
When weighing bundles of 25 articles, a uniform weight variation of only 2% in the typical individual article weight results in a bundle weight variation of 50% of the typical individual article weight, i.e., the normal tolerance. Thus, small, consistant weight variations in the weight of packaged articles cause errors in the article count per bundle.
In newspaper production, it has been found that newspapers typically vary in weight over significantly more than a 2% range. One cause of the weight change is the weight of the newspaper stock. The paper stock may vary in thickness, moisture content, and other characteristics which affect its average weight per unit area. A more pronounced variation in the newspaper weight is caused by variations in the moisture content of the ink. In an off-set printing process, the water content of the ink and other properties of the ink will fluctuate during a printing run. These changes tend to occur cyclically over large numbers of newspapers as ink vats are refilled, paper rolls changed, and the like.
The present invention contemplates a new and improved method and apparatus for weight measuring the number of articles in a package or bundle which overcomes the above-referenced problems and others.